The invention relates to rotors for use in impact crushers and analogous comminuting machines. More particularly, the invention relates to improvements in rotors of the type wherein the body of the rotor supports beater bars which come into contact with the material to be comminuted when the rotor is in use in an impact crusher or in an analogous comminuting machine.
It is known to assemble an impact crusher rotor from several coaxial discs which are mounted on a shaft and the peripheries of which are formed with recesses for reception of beater bars. The beater bars extend in parallelism with the axis of the rotor and are separably coupled to the discs. The means for coupling the beater bars to the discs comprises mating male and female detent elements provided on the rotor body and on the beater bars, and wedges which are disposed at the opposite sides of the beater bars and serve to prevent separation of male and female detent elements when the rotor is in use. The wedges are urged against the respective beater bars by fluid-operated thrust elements. All thrust elements for a set of wedges which engage a particular beater bar receive pressurized fluid from a common conduit which extends in substantial parallelism with the axis of the rotor. Each conduit receives pressurized fluid from a discrete connecting member which is equipped with a regulating valve.
Published German patent application No. 21 48 752 discloses an impact crusher wherein the body of the rotor is formed with integral conduits in the form of bores which convey pressurized fluid to the thrust elements for the wedges. Each conduit includes an axially extending bore which receives pressurized fluid from the main source, and radially extending bores which convey fluid from the axially extending bore to the thrust elements for the respective set of wedges. A drawback of the just outlined conventional rotor is that pressurized fluid is likely to leak at the discharge ends of the radially extending bores as a result of severe shocks to which the beater bars, the wedges and the thrust elements are subjected in actual use of the rotor. The repair of leaks is costly and lengthy with prolonged idleness of the entire impact crusher. Moreover, the drilling of holes or bores into the body of the rotor is a costly procedure which contributes significantly to the initial cost of the rotor.
Published German patent application No. 35 21 588 discloses a modified rotor which can be used in an impact crusher and wherein the wedges are provided with holes or bores for admission of pressurized fluid to the respective thrust elements. The thrust elements include pistons which are installed and are reciprocable in radially inwardly extending transverse holes drilled into the wedges. Pressurized fluid causes the pistons to bear against the body of the rotor and to thereby urge the wedges against the respective beater bars as well as against the body of the rotor.
A drawback of the just described rotor is that it must employ axially elongated wedges each of which extends along not less than one-half of the length of the rotor body. The reason is that each wedge (which has a fluid-supplying bore therein) must carry several pistons which are caused to bear against the rotor body in order to maintain the wedge in clamping position, i.e., to prevent disengagement of mating male and female detent elements which are provided on the beater bar and on the adjacent portion of the rotor body. An elongated wedge does not properly engage a beater bar because the beater bars are cast and have therefore a poor degree of accuracy. Moreover, the wedges are closely adjacent the periphery of the rotor body so that they are subjected to extensive wear and to pronounced shocks in actual use of the rotor. Therefore, these costly wedges must be replaced at frequent intervals with attendant increase of the maintenance cost.